This invention relates to an apparatus for use with an automobile for controlling a throttle valve situated for rotation within an engine induction passage.
In order to meter the amount of air to an internal combustion engine, a variable positionable throttle valve is situated within the induction passage of the engine. Normally, a mechanical link mechanism is provided to couple the throttle valve to an accelerator pedal in a manner to move the throttle valve in response to movement of the accelerator pedal. It has been proposed to employ such a mechanical throttle control apparatus with an electrical throttle control apparatus. For example, Japanese Patent Kokai No. 58-167845 discloses an electrical throttle control apparatus used with a normal mechanical throttle control apparatus. The electrical control apparatus is arranged to force the throttle valve to move in a closing direction when the slip factor exceeds a predetermined value. A serious problem which occurs with such a conventional throttle control system is the danger of the automobile going out of control due to unreasonable throttle valve opening operation which may be performed when trouble occurs in the electrical throttle control apparatus for a variety of reasons.